Cloudwatch: Fix issue with Grafana Assume Role (#84315)

pkg/tsdb/cloudwatch/cloudwatch.go

@@ -174,6 +174,23 @@ func (e *cloudWatchExecutor) getRequestContext(ctx context.Context, pluginCtx ba
 	}, nil
 }
 
+// getRequestContextOnlySettings is useful for resource endpoints that are called before auth has been configured such as external-id that need access to settings but nothing else
+func (e *cloudWatchExecutor) getRequestContextOnlySettings(ctx context.Context, pluginCtx backend.PluginContext, _ string) (models.RequestContext, error) {
+	instance, err := e.getInstance(ctx, pluginCtx)
+	if err != nil {
+		return models.RequestContext{}, err
+	}
+
+	return models.RequestContext{
+		OAMAPIProvider:        nil,
+		MetricsClientProvider: nil,
+		LogsAPIProvider:       nil,
+		EC2APIProvider:        nil,
+		Settings:              instance.Settings,
+		Logger:                e.logger.FromContext(ctx),
+	}, nil
+}
+
 func (e *cloudWatchExecutor) CallResource(ctx context.Context, req *backend.CallResourceRequest, sender backend.CallResourceResponseSender) error {
 	ctx = instrumentContext(ctx, "callResource", req.PluginContext)
 	return e.resourceHandler.CallResource(ctx, req, sender)

pkg/tsdb/cloudwatch/resource_handler.go

@@ -25,7 +25,7 @@ func (e *cloudWatchExecutor) newResourceMux() *http.ServeMux {
 	mux.HandleFunc("/accounts", routes.ResourceRequestMiddleware(routes.AccountsHandler, e.logger, e.getRequestContext))
 	mux.HandleFunc("/namespaces", routes.ResourceRequestMiddleware(routes.NamespacesHandler, e.logger, e.getRequestContext))
 	mux.HandleFunc("/log-group-fields", routes.ResourceRequestMiddleware(routes.LogGroupFieldsHandler, e.logger, e.getRequestContext))
-	mux.HandleFunc("/external-id", routes.ResourceRequestMiddleware(routes.ExternalIdHandler, e.logger, e.getRequestContext))
+	mux.HandleFunc("/external-id", routes.ResourceRequestMiddleware(routes.ExternalIdHandler, e.logger, e.getRequestContextOnlySettings))
 	mux.HandleFunc("/regions", routes.ResourceRequestMiddleware(routes.RegionsHandler, e.logger, e.getRequestContext))
 	// remove this once AWS's Cross Account Observability is supported in GovCloud
 	mux.HandleFunc("/legacy-log-groups", handleResourceReq(e.handleGetLogGroups, e.logger))

pkg/tsdb/cloudwatch/routes/external_id.go

@@ -14,8 +14,8 @@ type ExternalIdResponse struct {
 	ExternalId string `json:"externalId"`
 }
 
-func ExternalIdHandler(ctx context.Context, pluginCtx backend.PluginContext, reqCtxFactory models.RequestContextFactoryFunc, parameters url.Values) ([]byte, *models.HttpError) {
-	reqCtx, err := reqCtxFactory(ctx, pluginCtx, "default")
+func ExternalIdHandler(ctx context.Context, pluginCtx backend.PluginContext, reqCtxBeforeAuth models.RequestContextFactoryFunc, parameters url.Values) ([]byte, *models.HttpError) {
+	reqCtx, err := reqCtxBeforeAuth(ctx, pluginCtx, "")
 	if err != nil {
 		return nil, models.NewHttpError("error in ExternalIdHandler", http.StatusInternalServerError, err)
 	}